package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.conditions.query.QueryChainWrapper;
import com.hmdp.dto.Result;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Follow;
import com.hmdp.mapper.FollowMapper;
import com.hmdp.service.IFollowService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.service.IUserService;
import com.hmdp.utils.UserHolder;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

@Service
public class FollowServiceImpl extends ServiceImpl<FollowMapper, Follow> implements IFollowService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private IUserService userService;

    @Override
    public Result follow(long followUserId, Boolean isFollow) {
        //1、获得当前用户id
        Long userId = UserHolder.getUser().getId();
        //2、判断是关注还是取关
        if (isFollow) {
            //3、关注，insert into tb_follow (user_id, follow_user_id) values (?, ?)
            Follow follow = new Follow();
            follow.setUserId(userId);
            follow.setFollowUserId(followUserId);
            boolean isSuccess = save(follow);
            if(isSuccess){
                //5、把关注信息保存到Redis中
                String key = "follows:" + userId;
                stringRedisTemplate.opsForSet().add(key, String.valueOf(followUserId));
            }
        }else {
            //4、取关 delete from tb_follow where user_id = ? and follow_user_id = ?
            boolean isSuccess = remove(new QueryWrapper<Follow>()
                    .eq("user_id", userId)
                    .eq("follow_user_id", followUserId));
            if(isSuccess){
                //6、把关注信息从Redis中移除
                String key = "follows:" + userId;
                stringRedisTemplate.opsForSet().remove(key, String.valueOf(followUserId));
            }
        }
        return Result.ok();
    }


    @Override
    public Result isFollow(long followUserId) {
        //1、获得当前用户id
        Long id = UserHolder.getUser().getId();
        //2、查询数据库 select count(*) from tb_follow where user_id = ? and follow_user_id = ?
        Integer count = query().eq("user_id", id).eq("follow_user_id", followUserId).count();
        return Result.ok(count > 0);
//        // 如果 count > 0，说明有关注记录
//        if (count > 0) {
//            return Result.ok(true);   // 已关注
//        } else {
//            return Result.ok(false);  // 未关注
//        }
//
//// 等价于简写：
//        return Result.ok(count > 0);
    }

    @Override
    public Result followCommons(Long id) {
        // 1、获取当前用户
        Long userId = UserHolder.getUser().getId();
        //2、求交集
        String key1 = "follows:" + userId;
        String key2 = "follows:" + id;
        Set<String> commonUserSet = stringRedisTemplate.opsForSet().intersect(key1, key2);
        if (commonUserSet == null || commonUserSet.isEmpty()) {
            return Result.ok(Collections.emptyList());
        }
        //4、解析id集合
        List<Long> idList = commonUserSet.stream()
                .map(Long::valueOf)
                .collect(Collectors.toList());
        //3、查询相关用户，返回结果
        List<UserDTO> userDTOList = userService.listByIds(idList)
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());
        return Result.ok(userDTOList);
    }
}
